The present invention relates to heterocyclic compounds having a serotonin-3 (hereafter referred to as 5-HT.sub.3) antagonizing activity which compounds are useful as antiemetics and suppressants of migraine.
It is known that 5-HT.sub.3 antagonists exhibit an antiemetic activity, an antianxious activity, a suppressing activity of mental disorders, a suppressing activity of migraine, etc. [Trends in Pharmacological Sciences, 8, 501 (1987); hereafter referred to as TIPS]. 5-HT.sub.3 antagonists are effective against carcinostatic agent-induced vomiting, which has not been cured by dopamine antagonists. The 5-HT.sub.3 antagonists are thus expected to be antiemetics of new type [Br. J. Cancer, 56, 159 (1987)].
As 5-HT.sub.3 antagonists, an indole derivative ICS205-930: ##STR2## an indazole derivative, BRL43694: ##STR3## and the like are described in TIPS supra.
It is disclosed in Japanese Published Unexamined Patent Application No. 72886/85 (U.S. Pat. No. 4,797,406, GB-B-2145416) that quinoline derivatives represented by formula (A): ##STR4## wherein R.sup.A represents lower alkyl (C.sub.1 -C.sub.7); R.sup.B represents hydrogen or lower alkyl (C.sub.1 -C.sub.4); X.sup.1 represents --O-- or --NH--; and P represents 0 or 1, possess a 5-HT.sub.3 antagonizing activity and an antiarrhythmic activity. It is also disclosed in Japanese Published Unexamined Patent Application No. 4142988 (GB-A-2193633) that the above compounds represented by formula (A) are effective against vomiting caused by carcinostatic agents such as Cisplatin. It is further disclosed in Japanese Published Unexamined Patent Application No. 203365/89 (U.S. Pat. No. 4,983,600, EP-A-323077) that quinoline derivatives represented by formula (B): ##STR5## wherein R.sup.C represents hydrogen or hydroxyl; X.sup.B represents a single bond or CO; W represents oxygen or sulfur; Y represents NH or O; R.sup.D represents lower alkyl (C.sub.1 -.sub.6); and q represents 0 or 1, are useful as 5-HT.sub.3 antagonists.